Published 11:17 pm, Thursday, May 31, 2012

The Seattle area has the nation's third-strongest local economy, according to a new report looking at performance over an extended period.

Only Washington, D.C., and Des Moines, Iowa, were higher in research firm Policom Corp.'s annual ranking of 366 metropolitan areas. The study measures 23 different economic factors over 20 years (1991 to 2010, in this case).

"The top rated areas have had rapid, consistent growth in both size and quality for an extended period of time," Policom President William Fruth said in a news release. "The rankings do not reflect the latest 'hotspot' or boom town, but the areas which have the best economic foundation. While most communities have slowed or declined during this recession, the strongest areas have been able to weather the storm."

The Seattle area is King, Pierce and Snohomish counties. It finished third last year and first in 2010. The next-highest rated Washington area was the Tri-Cities, in 13th place, up from 35th in 2011, 70th in 2010 and 125th in 2009.

Policom also ranks 576 micropolitan areas, which have no city with more than 50,000 people. The top three in this category were Concord, N.H., Helena, Mont. and Lexington Park, Md. The top-ranked Washington area was Ellensburg, in 37th place.